In the bowl of a food processor, combine the pecans, flour, granulated and brown sugars, cinnamon, and salt. Pulse a few times until combined and the pecans are broken down, 5 or 6 pulses.

Pour the melted butter over the top and pulse again until the butter is incorporated, 3 or 4 more pulses.

Adjust an oven rack to the middle position and preheat the oven to 350F (180C). Grease eight 4 in (10 cm) springform pans or cake pans, and line the bottom with parchment.

In a large bowl, whisk together the granulated and brown sugars, buttermilk, eggs, melted butter, oil, vanilla, salt, and baking soda.

Add the bananas and whisk again to combine.

Add the flour and mix until incorporated, about 20 seconds.

Divide the batter evenly between the prepared pans, smoothing the tops with an offset spatula or the back of a spoon.

In the bowl of a stand mixer fitted with a paddle, beat together the cream cheese and granulated sugar on low speed until smooth and creamy.

Add the egg and mix until incorporated, scraping down the sides as needed.

Divide the cream cheese mixture among the pans and smooth the tops, getting as close to the edges as you can.

Sprinkle an equal amount of streusel over each cake top.

Place the cakes on the sheet pan into the oven and bake until a wooden skewer or toothpick inserted into the center comes out clean, about 25 to 35 minutes.

Transfer the pan to a wire rack and let the cakes cool until barely warm or at room temperature.

Remove the cakes from their pans and serve.